Fuel Flow Impingement Measurements on Multi-Orifice Diesel Nozzles

The injection process plays an important role in Diesel engines in terms of future emission legislations. Higher injection pressures and multiple injection events every cycle are a reality. To be able to understand how the fuel injection process can be further improved studies are needed on how higher pressure, multiple injections and multi orifice nozzles affect the overall process. The objective of this study was to further develop a measurement technique to determine injection rates and discharge coefficient for multi orifice nozzles. The technique used is based on measuring the instantaneous force of a fuel jet for a non-stationary injection process. The technique is applicable for multi orifice nozzles at high injection pressures. Both single and multiple injections can be resolved. The accuracy of the technique depends on the distance between the sensor and orifice, and the sensor should be mounted as close as possible to the orifice, which can be a problem for multi orifice nozzles. This is less difficult for higher injection pressures. A comparison between the flow of an injector used in an engine that was measured with the impingement technique showed that the difference in total flow was less than 3 %. The impingement also showed great differences between the holes.